The present disclosure generally relates to medical fluid delivery systems. In particular, the present disclosure relates to devices and methods for transforming a generally pulsatile fluid flow in an infusion system to a smoother or less pulsatile fluid flow.
Liquid medicaments and other complex medical and therapeutic fluids are often administered to patients through infusion therapy. Typically, infusion therapy is accomplished by employing an infusion pump to force fluid through an infusion circuit and into a patient. In certain situations, such as when the infusion of fluid takes place over a long period of time with a patient that is ambulatory, it is desirable to use a disposable infusion system.
Because disposable infusion systems are generally single-use items, such systems typically include relatively simple and inexpensive components. However, one of the difficulties encountered with using relatively simple and inexpensive components is that the components are often not compatible for use with one another. For example, the majority of simple and inexpensive infusion pumps generate a pulsatile or non-continuous fluid flow. Even durable and expensive pumps generate pulsatility. This pulsatile fluid flow is dynamic and has flowrate and pressure fluctuations that change very quickly. Further, most simple and inexpensive fluid flow sensors do not have the temporal resolution or the ability to sense and calculate the flowrate of a pulsatile fluid flow. The incompatibility of these components creates an obstacle to producing economical disposable infusion systems that have the ability to monitor the fluid flowrate within the infusion circuit.
In many infusion therapy applications a fluid is required to be administered to the patient at a certain fluid flowrate to be therapeutically effective. For example, in some applications, if the fluid is infused too slowly, the intended therapeutic effect may be diminished or totally non-existent. In other applications, infusion of a fluid into the body at too high a rate can create a dangerous or overdose situation. Thus, in a number of infusion therapy applications it is important for the user to be able to quickly and accurately determine the rate of fluid flow through the system, so that the flowrate can be monitored and adjusted as needed.
In those instances in which it is important for the user to be able to determine flowrate, a disposable infusion set will often include either an infusion pump that generates a smooth fluid flow or a flow sensor that has the ability to monitor and calculate the flowrate of a pulsatile or non-continuous fluid flow. One of the disadvantages of using a smooth flow generating infusion pump or a flow sensor that can monitor pulsatile flow is that both of those components are relatively expensive and add appreciably to the overall cost of the disposable infusion set. In addition to increased cost, system components that are capable of achieving high resolution measurements often require complex circuitry, hardware and software architecture.